feat: add master notebook library scaffolding and review tooling

Add CLAUDE.md defining the Palladium master notebook conventions and
Red Panda Approval criteria, plus a review-notebook slash command for
LLM-driven notebook review.

Expand .gitignore to block client/engagement documents and generated
exports, keeping masters client-clean while allowing text/image sources.

Normalize slider widget numeric values from floats to integers in
notebook JSON.

studies/202607_CTM_GenesysCX/notebooks/ctm_token_calculator.ipynb

@@ -42,7 +42,7 @@
     }
    ],
    "source": [
-    "# ── Setup ──────────────────────────────────────────────────────────\n",
+    "# ── Setup ──────────────────────────3rd with just the────────────────────────────────\n",
     "import sys, pathlib\n",
     "_ROOT = pathlib.Path.cwd()\n",
     "if not (_ROOT / \"tokencalc\").exists():           # notebook lives in notebooks/\n",
@@ -8847,7 +8847,7 @@
        "disabled": false,
        "layout": "IPY_MODEL_d68795b0944341bf8354500e127e4e59",
        "max": 0.5,
-       "min": 0.0,
+       "min": 0,
        "orientation": "horizontal",
        "readout": true,
        "readout_format": ".0%",
@@ -8940,7 +8940,7 @@
        "description_allow_html": false,
        "disabled": false,
        "layout": "IPY_MODEL_3462a88bfec94f01b6aea7530a431884",
-       "max": 5.0,
+       "max": 5,
        "min": 0.5,
        "orientation": "horizontal",
        "readout": true,
@@ -9105,7 +9105,7 @@
        "disabled": false,
        "layout": "IPY_MODEL_9fe19d91747e4865a104e65b658b7c8e",
        "max": 0.7,
-       "min": 0.0,
+       "min": 0,
        "orientation": "horizontal",
        "readout": true,
        "readout_format": ".0%",
@@ -9334,7 +9334,7 @@
        "description_allow_html": false,
        "disabled": false,
        "layout": "IPY_MODEL_fd591354d1214f4b9b7d8850be81a511",
-       "max": 1.0,
+       "max": 1,
        "min": 0.3,
        "orientation": "horizontal",
        "readout": true,
@@ -9434,7 +9434,7 @@
        "description_allow_html": false,
        "disabled": false,
        "layout": "IPY_MODEL_4c9514e9b96142e9a269035bdd0714c4",
-       "max": 1.0,
+       "max": 1,
        "min": 0.3,
        "orientation": "horizontal",
        "readout": true,
@@ -9483,7 +9483,7 @@
        "disabled": false,
        "layout": "IPY_MODEL_995b326fefa942da94ce18e92254860e",
        "max": 0.3,
-       "min": 0.0,
+       "min": 0,
        "orientation": "horizontal",
        "readout": true,
        "readout_format": ".0%",